Vacuum Cleaner Agitator Clutch

ABSTRACT

A vacuum cleaner clutch assembly having an input driven by a motor, an output to drive an agitator, a starter clutch and a drive clutch. The starter clutch moves between an engaged position in which it receives a first drive torque from the input, and a disengaged position in which it receives substantially no torque directly from the input. The drive clutch is moveable between an engaged position in which it receives a second drive torque from the input, and a disengaged position in which it receives substantially no torque directly from the input. When engaged, the starter clutch is coupled to the drive clutch to transmit the first drive torque to the drive clutch to move the drive clutch into the engaged drive clutch position. When engaged, the drive clutch is coupled to the clutch assembly output to transmit the second drive torque to the output.

FIELD OF THE INVENTION

The present invention relates to clutch assembly features for use withvacuum cleaners. More specifically, the present invention relates to aclutch assembly for transferring power from a vacuum cleaner motor unitto the brushroll. It will be understood that the features of the clutchassembly may be used in other types of equipment and/or appliances, andmay be used in part, and in combination with other driveline features.

BACKGROUND OF THE INVENTION

It is well known that vacuum cleaners, such as upright vacuums, may usea rotating brushroll to help clean various surfaces, such as carpeting.Canister type vacuum cleaners may also use a power head having arotating brushroll, as is known in the art. The brushroll typicallyrotates about a horizontal axis and provides surface agitation torelease dirt and dust trapped in and upon the surface being cleaned.Once agitated, the dirt and dust are sucked into the vacuum cleanerthrough the dirty air inlet. Suction force is typically generated by afan motor unit.

The brushroll is typically driven by a motor. The vacuum may have onemotor that provides both suction and drive power for the brushroll (aso-called “single-motor” vacuum). Alternatively, the vacuum may have twomotors—one for generating suction and one for driving the brushroll.Such a “two-motor” vacuum configuration may have the drawback ofincreased weight and cost, but may be favored where separate control ofthe suction fan and brushroll are desired, or the fan motor is for somereason not capable of driving the brushroll. Power from a motor, in anyconfiguration, must be transferred from the motor to the brushroll. Thebrushroll may be driven at a slower rotational speed than the motor. Forexample, a motor may operate at over 10,000 revolutions per minute(rpm), and it may be desirable to rotate the brushroll at a slowerspeed, such as 3,000 rpm. As is known in the art, a drive belt istypically used for driving the brushroll. The belt typically is a highstrength, long life belt that may be flat or ridged or toothed. Areduction gear and clutch mechanism may be provided. A cogged beltand/or reduction gears also may be used to provide gearing reduction.Some vacuums may alternatively use a direct drive from the motor to thebrushroll, or incorporate the motor in the brushroll.

While brushrolls are commonly used and typically beneficial, theypresent a potential problem in that the brushroll may continue to rotateeven when it is not desirable. For example, rotation may continue whenthe vacuum is stopped or placed into an upright position with the powerstill on, or when cleaning smooth floors that may not benefit from abrushroll. In fact, damage to the surface below the rotating brushrollmay result from the brushroll rotating in one place. For example, carpetfibers may become worn or burned from frictional heat generated from thecontinuous rotation of the brushroll over a small part of the carpet. Ina typical single-motor vacuum with a direct drive brushroll, there maybe no independent control over the brushroll, such that in order to stopthe brushroll, the vacuum itself may need to be turned off. Somesingle-motor vacuums may incorporate a lifting mechanism for thebrushroll, which lifts the brushroll off the floor when the vacuum isplaced in the upright position or when it is desired to clean smoothfloors, but the rotation of the brushroll may continue. In otherdesigns, an idler pulley configuration may be used, in which the drivebelt is placed upon an idler pulley when the vacuum is placed in theupright position or when it is desired to clean smooth floors, stoppingthe brushroll rotation. In such devices, the driven belt must bereplaced upon the driven pulley to resume operation, which oftenrequires a mechanically complex and potentially unreliable mechanism todisengage and engage the brushroll. In other cases, a clutch mechanismmay be used to disengage the brushroll.

Two-motor vacuum cleaners have potential to provide greater control overwhen the brushroll is rotating, because the brushroll motor can beoperated by manually or automatically operated switches to turn thebrushroll on and off independently of the vacuum source motor. Suchdevices can be heavier and more expensive than single-motor vacuums.

Another potential problem with brushrolls is that they can becomejammed. For example, a foreign object may become lodged into thebrushroll and prevent rotation. When this happens, the drive motor couldoverheat (particularly if the motor stops when the brushroll stops)and/or the drive belt or other drive mechanisms could be damaged. Duringsuch jams, it is desirable to disengage or stop drive power to thebrushroll to prevent damage to the vacuum or the foreign object. Somevacuums use thermally-operated switches to cut off power to the motorwhen an overheating condition is reached. Other vacuums use anon-replaceable fuse that renders the vacuum inoperative and irreparableif the motor locks. The vacuum also may be designed with the belt as theweakest link, so that the belt typically fails during a severe jamcondition. Still other vacuums use a clutch mechanism which maydisengage or slip under a high torque condition.

Different clutch mechanisms are known in the art. Clutch mechanisms areused to provide both a power transfer function and a torque limitingfunction through the use of various structural configurations, such asfriction plates, flexible couplings, springs, detent plates, waveplates, and magnetic couplings. Exemplary clutch mechanisms withapplication to vacuums incorporating some of the aforementioned featuresare described in U.S. Pat. Nos. 3,228,209; 3,797,621; 4,235,321;4,532,667; 4,766,641; 5,601,491; 6,691,849; and 7,228,593; whichreferences are incorporated herein.

It has been found that many different requirements may be desired ofvacuum cleaner brushroll drive and clutch mechanisms. For example, suchrequirements sometimes include: operate in the overload condition for along time without overheating; survive numerous disengagement andreengagement cycles; operate automatically to address different cleaningmodes (e.g., turn off the brushroll during accessory cleaning operationsand when vacuuming on bare floors); operate manually to allow the userto selectively disengage the brushroll; operate in dusty environments;and so on. Some of these requirements may oppose one another in variousrespects. For example, it is desirable to provide a brushroll overloadclutch that will disengage drive torque to the brushroll immediatelyupon reaching an overload torque value, to better protect any objectsthat contact the brushroll, the brushroll, and the drive components.While this could be accomplished using an overload clutch having arelatively low overload torque value, the clutch may be so sensitivethat it will disengage when it is not desired, such as when thebrushroll is started on thick carpets or moved rapidly from a smoothsurface to a carpeted surface.

While various prior art devices, such as those described above, havebeen used, there exits a need to provide alternatives to such devices.

SUMMARY OF THE INVENTION

In a first exemplary aspect, there is provided a clutch assembly for avacuum cleaner. The clutch assembly includes an input adapted to bedriven by a motor, an output adapted to drive an agitator, a starterclutch and a drive clutch. The starter clutch is moveable between anengaged starter clutch position in which the starter clutch receives afirst drive torque from the clutch assembly input, and a disengagedstarter clutch position in which the starter clutch receivessubstantially no torque directly from the clutch assembly input. Thedrive clutch is moveable between an engaged drive clutch position inwhich the drive clutch receives a second drive torque from the clutchassembly input, and a disengaged drive clutch position in which thedrive clutch receives substantially no torque directly from the clutchassembly input. The starter clutch is coupled to the drive clutch suchthat the starter clutch, when in the engaged starter clutch position,can transmit the first drive torque to the drive clutch to move thedrive clutch into the engaged drive clutch position. The drive clutch iscoupled to the clutch assembly output such that the drive clutch, whenin the engaged drive clutch position, can transmit the second drivetorque to the clutch assembly output. In various other aspects, theclutch assembly may include an overload clutch that disengages torquetransfer from the clutch assembly input to the clutch assembly output.

In another exemplary aspect, there is provided a clutch assembly for avacuum cleaner in which the clutch assembly has a clutch assembly inputadapted to be driven by a motor, a clutch assembly output adapted todrive an agitator, a drive clutch adapted to selectively transmit adrive torque from the clutch assembly input to the clutch assemblyoutput, and a starter clutch adapted to selectively engage the driveclutch by transmitting a starting torque from the clutch assembly inputto the drive clutch.

In another exemplary aspect, there is provided a clutch assembly for avacuum cleaner in which the clutch assembly has a clutch assembly inputadapted to be driven by a motor, a clutch assembly output adapted todrive an agitator, and a drive clutch adapted to selectively transmit adrive torque from the clutch assembly input to the clutch assemblyoutput. The drive clutch includes a self-adjusting clutch that increasesthe drive torque as a rotational resistance of the clutch assemblyoutput increases.

The recitation of this summary of the invention is not intended to limitthe claimed invention. Other variations are encompassed by the appendedclaims and disclosed herein, and other aspects, embodiments,modifications to and features of the claimed invention will be apparentto persons of ordinary skill in view of the disclosures herein.Furthermore, this recitation of the summary of the invention, and theother disclosures provided herein, are not intended to diminish thescope of the claims in this or any related or unrelated application.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in detail with reference to theexamples of embodiments shown in the following figures in which likeparts are designated by like reference numerals.

FIG. 1A is a fragmented perspective view of a vacuum cleaner baseassembly in accordance with an exemplary first embodiment.

FIG. 1B is a schematic side view of the vacuum cleaner base assembly ofFIG. 1A.

FIG. 2 is a perspective view of a clutch assembly and mounting andsupport structure in accordance with an exemplary first embodiment.

FIG. 3 is a first perspective view of the mounting and support structurefor the clutch assembly of FIG. 2.

FIG. 4 is a second perspective view of the mounting and supportstructure for the clutch assembly of FIG. 2.

FIG. 5 is a perspective view of the clutch assembly of FIG. 2.

FIG. 6 is an exploded view of the clutch assembly and mounting andsupport structures of FIG. 2.

FIG. 7 is a cut-away view of the clutch assembly of FIG. 2.

FIG. 8 is a perspective view of a flywheel and drum assembly of theclutch assembly of FIG. 2.

FIG. 9 is a perspective view of a clutch lever of the clutch assembly ofFIG. 2.

FIG. 10A is a perspective view of an expanding clutch assembly of theclutch assembly of FIG. 2.

FIG. 10B is a schematic end view of the expanding clutch assembly ofFIG. 10A, showing the expanding clutch in a disengaged position.

FIG. 10C is a schematic end view of the expanding clutch assembly ofFIG. 10A, showing the expanding clutch in an engaged position.

FIG. 11 is a perspective view of an inner overload device of the clutchassembly of FIG. 2, showing the device in a normal operating condition.

FIG. 12 is a perspective view of an inner overload device of FIG. 11,showing the device in the overload condition.

FIG. 13A is an end view of an alternative embodiment of a clutchengagement mechanism, shown in the disengaged position.

FIG. 13B is an end view of the clutch lever of FIG. 13A shown in theengaged position.

FIG. 14 is a cut-away view of a clutch assembly in accordance withanother alternative embodiment.

FIG. 15 is a side view of an overload mechanism in accordance with analternative embodiment.

FIG. 16A is a side view of an alternative exemplary embodiment of aclutch assembly shown in the disengaged position.

FIG. 16B illustrates the assembly of FIG. 16A in the engaged position.

FIG. 16C illustrates the assembly of FIG. 16A in the overload condition.

FIG. 17 is a side view of a clutch mechanism in accordance with anotheralternative embodiment.

FIG. 18A is a side view of a clutch mechanism in accordance with anotheralternative embodiment.

FIG. 18B is a side view of the clutch mechanism of FIG. 18A in theengaged position.

FIG. 18C is a side view of the clutch mechanism of FIG. 18A in thedisengaged position.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTIONS

The present disclosure provides numerous inventive features relating toembodiments of a clutch assembly for use in a vacuum cleaner or in otherappliances or machines. Various features and alternative embodiments ofthe invention are described with reference to their exemplary use incertain embodiments, but it will be readily appreciated that thefeatures could alternatively be incorporated into other embodiments ofvacuum cleaners. The invention includes these and other variations, aswill be appreciated by persons of ordinary skill in the art in view ofthe present disclosure. Furthermore, the various features describedherein may be used separately from one another or in any suitablecombination. The present disclosure illustrating various exemplaryembodiments is not intended to limit the invention in any way.

An exemplary first embodiment of the invention is illustrated in FIGS.1-12, which generally illustrate a clutch assembly 100 for an uprightvacuum, canister vacuum power head, or any other type of vacuum cleanerthat uses a driven brushroll. The descriptions herein of this embodimentand other embodiments of the clutch assembly 100 will focus onapplication in a vacuum cleaner, but it will be understood that theclutch assembly 100 may be used in other types of equipment andappliances. For example, the clutch assembly 100 has application to anymechanism that may require a transfer of power, in the form ofrotational energy or torque, from an input (such as a motor drive) to adriven output (such as a brushroll), in which it is desired to provide ameans to engage and disengage the driven output on command or duringoverload conditions. As will be appreciated from the disclosure herein,the exemplary clutch assembly 100 may be configured to provide bothoverload protection to the equipment (such as by decoupling the outputdrive from the input drive), and a means for selectively engaging anddisengaging the motor from the driven assembly to initiate and ceaseoperation of the driven assembly when desired. However, these twofeatures and functions may be provided separately, and are not requiredin all embodiments of the invention.

As shown in FIG. 1A, the exemplary clutch assembly 100 may be mounted ina base assembly 110 of a vacuum cleaner. The base assembly 110 is shownwith the upper cover removed to depict the clutch assembly 100 anddriven agitator, such as a brushroll 102. In this embodiment, a fanmotor 104 is provided to simultaneously drive a vacuum fan and theclutch assembly 100. The fan motor 104 may be mounted in the baseassembly 110, or mounted in an upright housing 112 that is pivotallymounted to the base assembly 110, as known in the art. Examples of fanmotor locations are shown in U.S. Pat. Nos. 6,122,796, 6,553,611, and5,014,388, which are incorporated herein. The base assembly 110 also maycomprise the frame of a self-propelled vacuum cleaner, such as shown inU.S. Pat. No. 5,781,960, which is incorporated herein. Alternatively,the fan motor 104 may be replaced by another motor that does not drive avacuum fan. As will also be appreciated, the brushroll 102 may compriseor be replaced by any suitable agitator device, as are well-known in theart. For example, an exemplary agitator may include a rotating spindlehaving helical rows of flexible bristles, flexible flaps, rigid beaterbars, or combinations of such devices that are intended to contact andagitate the surface being cleaned to help dislodge or remove dirt fromthe surface.

The location of the clutch assembly 100 may be based on space, weight,and power transmission considerations for the particular vacuum cleaneror specific application, as known in the art, and it may be located inalternate positions from that depicted in FIG. 1. The base assembly 100may be located on or form part of an upright vacuum cleaner or a powerhead of a canister or central vacuum cleaner. Examples of uprightvacuums are provided above, and examples of power heads are provided inU.S. Pat. Nos. 4,467,495 and 4,614,003, which are incorporated herein byreference.

In the exemplary embodiment, the fan motor 104 drives a motor outputgear 120, which is drivingly connected to a clutch input gear 130 on theclutch assembly 100 by a motor belt 107. The motor belt 107 may be anytype of belt, such as a toothed belt with a plurality of spaced teeth onan inner surface thereof to engage with the spaced teeth of the firstand clutch input gear wheels. The drive belt may be a reinforced, highstrength belt for durability and lasting function. In other embodiments,a flat, ribbed or v-type drive belt may be used, as known in the art. Ofcourse, the motor output gear 120 and clutch input gear 130 may bereplaced with other types of pulley, cog or gear, as necessary ordesired to accommodate power transfer from the motor 104 to the clutchassembly 100.

As depicted in FIG. 1A, the motor output gear 120 may have a smallerdiameter than the clutch input gear 130. The diameter size differencemay provide a speed reduction, such that the clutch input gear 130 mayrotate slower than the motor output gear 120. This speed reduction maybe desirable because a typical vacuum motor may operate at a speedgreater than the desired brushroll speed.

The exemplary clutch assembly 100 may also have a clutch output gear140. The clutch output gear 140 may be connected by a brushroll belt 108(FIG. 1B) to a brushroll input gear 106 that drives the brushroll 102.The brushroll input gear 106 may be any suitable gear or pulley, and maybe located on, inside, or adjacent to the brushroll. The clutch outputgear 140, brushroll belt 108 and brushroll input gear 106 may compriseany suitable kind of gear or belt. For example, the brushroll belt 108may be a toothed belt similar to the motor belt 107, or may be flat,ribbed, or otherwise shaped. The difference in size between the clutchoutput gear 140 and the brushroll input gear 106 may provide a furthergear reduction. For example, the fan motor 104 may operate at about30,000 RPM and the brushroll may operate at about 4,000 RPM, with atotal gear reduction ratio of about 7.4:1. While in some embodiments,the brushroll may operate at a speed of over one thousand RPM, speedsbelow this may be possible in other embodiments. Of course, otherreduction ratios may be used in other embodiments (for example, theclutch input gear 130 may be the same diameter as the clutch output gear140), and in still other embodiments there may be no reduction or even aspeed-increasing ratio.

The clutch assembly 100 may be mounted to the base assembly 110 in anysuitable way. For example, the clutch assembly 100 may be mounted in thesame way a typical brushroll motor would be mounted in a typical vacuumcleaner base or powerhead. Such a mounting may be by one or morefasteners, such as screws, straps or bolts. In an exemplary embodiment,a clutch assembly mount 212, such as hereinafter described, may be used.The clutch assembly 100 also may be compression fitted into the baseassembly, such as by using a snap tight fit with plastic tabs. One ormore elastic bushings may be located between the clutch assembly 100 andthe base assembly 110 to reduce vibrations and/or accommodate variationsin manufacturing tolerances. It may also be desirable to make the clutchassembly 100 removable from the base assembly to facilitate repairs andmaintenance. Of course, in other embodiments, the clutch assembly 100may not be removable from the base assembly 110.

FIG. 2 depicts the clutch assembly 100 removed from the base assembly110 to help illustrate an exemplary clutch assembly mount 212. FIGS. 3and 4 depict the clutch assembly mount 212 with the clutch assembly 100removed. As shown, the exemplary clutch assembly mount 212 may includean outer base module 202, an outer bearing holder 204, an inner basemodule 206, and an inner bearing holder 208 (as used in reference to theclutch assembly mount 212, the terms “outer” and “inner” refer topositions with respect to the centerline of the base assembly 110). Inthis embodiment, the clutch assembly 100 is secured, at one end, by theouter base module 202, and, at the other end, by the inner base module206. The outer and inner base modules 202, 206 may be secured to thebase assembly 110 with one or more fasteners (not shown). The outer andinner bearing holders 204, 208 are mounted to the upper surfaces of theouter and inner base modules 202, 206, respectively. The outer and innerbearing holders capture bearings 604 a, 604 d (see FIGS. 5 and 6) inplace to thereby rotatably mount the clutch assembly 100 in the clutchassembly mount 212. The bearings 604 a, 604 d are secured in cavities402, 404 (FIG. 4) that are shaped to hold the bearings 604 a, 604 d. Thecavities 402, 404 may have ridges, such as shown, to accommodate andsecurely hold the bearings 604 a, 604 b against axial movement. Whilebearings may be used on some embodiments, journals or other rotatingmounting structures may be used to rotatably hold the clutch assembly100 in the clutch assembly mount 212.

The clutch assembly mount 212 may include other functional or structuralelements, such as a cut-out 406 to mount and support a solenoid 210. Thepurpose of the solenoid 210 is described subsequently herein. The clutchassembly mount 212 may also include, for example, pivot mounts 214 topivotally hold corresponding pivots 503 on a disengagement lever 502, asdescribed below. If desired, the clutch assembly mount may also includeshroud 121 that encases the clutch assembly 100, and an air passage 123to a vacuum source, such as a suction inlet passage 122 in the baseassembly 110. In such an embodiment, the vacuum source may draws airthrough the shroud and over the clutch assembly 100 to cool the clutchassembly 100 and remove any particulate matter that the clutch assembly100 may generate during use.

Turning to FIGS. 5-7, the first exemplary embodiment of a clutchassembly 100 is described in detail. The external features of the clutchassembly 100 are best shown in FIG. 5, with the clutch assembly mount212 removed. As shown, the clutch assembly 100 may have a clutch inputgear 130, a clutch output gear 140, a solenoid 210 with a solenoid shaft504, a disengagement lever 502, a flywheel 508 with a perimeter weight506, and a flywheel spring holder 510.

The clutch assembly 100 may receive an input, in the form of rotationaltorque, through the clutch input gear 130, as described above. Generallyspeaking, the clutch assembly 100 of this exemplary embodiment transfersthe input torque to the clutch output gear 140, as briefly describedabove. In the hereinafter described first exemplary embodiment, theclutch assembly 100 may provide several functions. First, it includesmechanisms that selectively provide torque transfer from the clutchinput gear 130 to the clutch output gear 140 in an engaged position, andprevent such torque transfer in a disengaged position. This aspect isreferred to sometimes herein as the drive clutch feature. Second, itincludes mechanisms that automatically prevent or substantially reducetorque transfer from the clutch input gear 130 to the clutch output gear140 upon detecting an overload condition. This aspect is referred tosometimes herein as the overload clutch feature. Thus, in this exemplaryembodiment, the clutch assembly 100 may be set in an engaged position inwhich torque is intended to be transferred from the clutch input gear130 to the clutch output gear 140, but such torque transfer may beprevented due to an overload condition. Further, the mechanisms theterminate torque transfer after sensing an overload may not allowtransmission of torque until after the clutch assembly has been reset tothe disengaged position.

In the exemplary embodiment, the drive clutch feature defaults to theengaged position. That is, power is transferred via the clutch assembly100 from the clutch input gear 130 to the clutch output gear 140 unlessthe clutch assembly 100 is set to a disengaged position. Any suitablemechanical or electrical device may be used to move the clutch assembly100 into the disengaged position. In the exemplary embodiment the clutchassembly 100 is disengaged by moving the flywheel 508 and its associatedflywheel weight 506 away from engagement with a drum 608 and itsassociated drum lid 609. The manner in which this accomplishes clutchdisengagement is described in detail below. In this exemplaryembodiment, the flywheel 508 is biased into engagement with the drum 608by a spring 622 (FIG. 6) that is captured between the flywheel springholder 510 and the flywheel 508. The flywheel weight 506 is formed aspart of the flywheel 508 or rigidly connected to it.

The disengagement lever 502 is provided to move the flywheel 508 againstthe bias of the spring 622. This is done by pivoting the disengagementlever 502 (which rotates on its pivots 503) away from the drum 608. Anysuitable mechanism may be used to move the disengagement lever 502. Forexample, a solenoid 210 having a solenoid shaft 504 that extends whenthe solenoid is activated, may be positioned adjacent the disengagementlever 502. When the solenoid 210 is energized, the shaft 504 extends andmoves the disengagement lever 502 away from the drum 608. As thedisengagement lever 502 pivots, its side surface 507 presses against andmoves the flywheel 508 (via contact with the flywheel weight 506) awayfrom the drum 608, thereby disengaging the clutch mechanism 100. Theside surface 507 may frictionally engage the flywheel 508 to decelerateit when it is disengaged, and the disengagement lever 502 may press theopposite side of the flywheel into frictional engagement with othersurfaces, such as an inner wall of the clutch assembly mount 212 to helpdecelerate the flywheel 508 and its weight 506.

Although it is not required, the foregoing arrangement is beneficialbecause it provides control over the clutch assembly 100 withoutrequiring significant effort to engage and disengage the working parts.In particular, the disengagement lever 502 obtains a significantmechanical advantage to press against the biasing force of the spring622, which provides a simple arrangement that facilitates easydisengagement of the clutch assembly 100, either by hand or by asuitable mechanical or electrical device. Furthermore, as discussed inmore detail below, it may not be necessary for the frictional forcesbetween the flywheel 508 and drum 608 to be particularly great in orderto engage the clutch assembly 100, and therefore the spring 622 need nothave a particularly high biasing force. This also reduces the amount offorce necessary to move the disengagement lever 502 and eases therequirements to operate the system.

It will be readily appreciated that various modifications or changes maybe made to the clutch assembly 100 to provide for engagement anddisengagement. For example, the solenoid 210 may be replaced by ahand-operated lever, and the disengagement lever 502 may be replacedwith other structures that move the flywheel 508 out of engagement. Instill other embodiments, the clutch assembly 100 may be biased in thedisengaged position, and require input to engage it, or the clutchassembly 100 may not be biased in either the engaged or disengagedposition.

FIG. 6 is an exploded view of the clutch assembly 100 and FIG. 7 is acut-away view of the internal components of the clutch assembly 100. Asbest seen in FIG. 7, a shaft 602, such as a steel axle, runs the lengthof the clutch assembly 100, and is used to transfer torque from theclutch input gear 130 to the clutch output gear 140. Certain parts ofthe clutch assembly 100 may be fixed to rotated with the shaft 602. Forexample, in accordance with the first embodiment, an overload cog 616(described below) and the clutch output gear 140 are fixed to the shaft602. Parts that are fixed to the shaft 602 may be secured using anysuitable method. For example, the overload cog 616 and clutch outputgear 140 may be secured by pins that pass through corresponding holesthrough the shaft 602. Other forms of mounting may includepress-fitment, threads, keys, and eccentric mating shapes (such as aD-shaped shaft and corresponding D-shaped holes through the fixedparts). Other parts may be fixed to the shaft 602, as well. For example,in this first exemplary embodiment, the end bearing 604 a may be pressedonto the end of the shaft 602 to capture parts in place between thebearing 604 a and the overload cog 616.

As noted above, the shaft 602 is rotatably mounted by two bearings 604a, 604 d. Additional bearings may be used to support the shaft 602, andto rotatably mount other parts on the shaft 602. For example, in anexemplary embodiment, at least six bearings, 604 a, 604 b, 604 c, 604 d,604 e, and 604 f may be provided. In addition, the bearings 604 a-f maybe plain roller or ball bearings, but may be replaced by other kinds ofrotating mounts, such as bushings or journal bearings. In this firstembodiment, the bearings 604 a-f may be the same type, but differenttypes of bearings or rotating mounts may be mixed together. The rotatingmounts may allow some axial movement of the parts they support, but theyalternatively may hold the supported part in a fixed axial locationalong the shaft 602. The bearings 604 preferably are sealed, durable andlast for the life of the vacuum cleaner, but they may require periodicmaintenance.

As noted above, the clutch assembly 100 of the exemplary firstembodiment provides a selective clutch function and an overload cutofffunction. The clutch assembly 100 may be arranged such that clutchmechanism and overload mechanism are located together within theconfines a single structural component. Such an arrangement may providea relatively compact structure, enabling installation in aspace-constrained environment, such as the base assembly 110 of a vacuumcleaner, as described above. For example, a single cylindrical modulelocated generally within the clutch input gear 130 may contain theclutch and overload mechanisms. As shown in FIGS. 6-8, this module maycomprise a drum 608 with a drum lid 609. It should be appreciated thatin other embodiments, the clutch mechanism and/or the overload mechanismmay be located in a more linear arrangement, such that the components ofthe clutch assembly are spaced out over the length of the shaft, and itis not required to contain the clutch and overload mechanisms in acommon unit like the drum 608.

In the present exemplary embodiment, the drum 608 comprises a generallycylindrical structure that is open at one end, and closed at the other.The drum 608 is rotatably mounted to the shaft 602 by one or morebearings or bushings, such as the shown two bearings 604 b and 604 c.Such rotating mounts may be spaced apart to help distribute any loads onthe drum 608 that may be caused by belt tension or other factors. Thedrum lid 609 covers the end of the drum 608 to contain the internalclutch and overload mechanisms. The clutch input gear 130 surrounds thedrum 608, and is rigidly fixed thereto by any suitable means, such asadhesives, press fitment, locking parts or other fasteners. The clutchinput gear 130 also may be formed integrally with the drum 608. In theexemplary embodiment, the clutch input gear 130 or drum 608 may includevents 611 that help dissipate the heat that may develop in the drum 608.As explained below, the drum lid 609 may provide a frictional contactpoint for the flywheel weight 506. Thus, the drum lid 609 and flywheelweight 506 may be formed of heat-resistant materials, such as metal orheat-resistant plastic.

The clutch and overload mechanisms may be contained within the drum. Inone embodiment, the clutch mechanism may generally surround the overloadmechanism, although it should be appreciated that the overload mechanismmay merely be within the confines of the clutch mechanism oralternatively located co-incidentally with or adjacent to the clutchmechanism. For example, the overload mechanism may be between the clutchinput gear 130 and the clutch output gear 140. The overload mechanismalso may be located remotely from the clutch mechanism in otherembodiments.

Any suitable drive clutch mechanism may be used to selectively transfertorque from the clutch input gear 130 to the clutch output gear 140(assuming the overload mechanism is not preventing such transfer). Forexample, the drive clutch mechanism may comprise a single stage clutchthat essentially immediately transfers all torque from the clutch inputgear 130 to the clutch output gear 140 (e.g., a simple “dog” clutchhaving parts that physically interlock to transfer torque).Alternatively, the drive clutch mechanism may comprise a graduatedengagement clutch that transfers torque from the clutch input gear 130to the clutch output gear 140 gradually or in blended or discretestages. A simple graduated engagement clutch might comprise, forexample, a disk clutch like those used in typical automotiveapplications, which, depending on the speed with which it is engaged,can smoothly increase the torque over time. Another graduated engagementclutch may comprise one having multiple clutches. For example, a firstclutch may provide an initial rotational energy and/or initial transferof torque from the clutch input gear 130 to the clutch output gear 140,and a second clutch may be engaged after the first clutch to provideincreased torque transfer. Arrangements that provide a significantlygraduated torque transfer may be referred to as a “soft-start” driveclutch system. Examples of such devices are described below, but otherembodiments may use other types of clutch mechanism.

As stated above, an overload mechanism may be provided to terminatetorque transfer. Such a mechanism may operate in conjunction with orindependently from a clutch mechanism. For example, the overloadmechanism may be an overload clutch that decouples the clutch outputgear from the clutch mechanism when an excessive resistance torque isapplied to the clutch output gear. The overload clutch may be aresistance clutch, such as one that uses friction devices and/ormagnetic forces, or any other suitable clutch device. Thepresently-discussed exemplary embodiment provides clutch and overloadmechanisms, which are described together below, but may be usedindependently in other embodiments.

In the first exemplary embodiment, a drive clutch mechanism may includean expanding clutch 610, a clutch lever 612, a clutch mount 614, and anoverload spring 618. In the shown embodiment, all of the foregoing partsare located within the drum 608, but this is not required. The flywheel508 operates the clutch lever 612, as described below. The clutch mount614 is located within the circumference of the expanding clutch 610 androtatably mounted on the shaft 602 by a bearing 604 e or bushing. Theclutch mount 614 provides a stable mounting plane for the expandingclutch 610, the clutch lever 612 and the overload spring 618. As shown,the expanding clutch 610 may surround the clutch mount 614, while theclutch lever 612 and overload spring 618 are mounted to opposite facesof the clutch mount 614.

The clutch lever 612 is pivotally connected to the clutch mount 614,such as by a pivot pin 624. The expanding clutch 610 comprises agenerally C-shaped structure that is mounted at one end to the clutchmount 614 by a first pin 626, and at the other end to the clutch lever612 by a second pin 628. Rotation of the clutch lever 612 about itsmounting pin 624 transmits a force to the second pin 628 that tends toincrease the size of the opening in the C-shaped expanding clutch 610,which increases the diameter of the expanding clutch 610. The first andsecond pins 626, 628 may be mounted in slots on the expanding clutch 610to allow some radial movement as the expanding clutch 610 expands andcontracts and accommodate any wear the parts might experience. Suchslots may also provide a ramp-like structure against which the pins 626,628 can press to generate an outward (or inward) radial component to theopening force applied by the clutch lever 612.

In the exemplary embodiment, the clutch lever 612 is operated by theflywheel 508. As noted above, the flywheel 508 is biased by a spring 622into engagement with the end of the drum 608. Contact may be directlybetween the flywheel 508 and drum 608, or via one or more added parts,such as shown. The flywheel 508 is rotatably mounted on the shaft 602 bya bearing 604 f (FIG. 7), and can rotate on the shaft 602 independentlyfrom the drum 608. When the clutch is in the engaged position, which isthe default position in this embodiment, the flywheel 508 contacts thedrum 608. In this position, rotation imparted to the drum 608 (via theclutch input gear 130) tends to rotate the flywheel 508 by frictionalcontact between these parts. If the flywheels' resistance to rotation isgreat enough, the frictional contact will be insufficient to drive theflywheel 508 at the same speed as the drum 608, or, in some cases, todrive the flywheel 508 at all. Conversely, where the flywheel 508 hasrelatively little resistance to rotation, it may rotate at the samespeed as the drum 608. Friction and inertia can both contribute to theflywheel's resistance to rotation at any given moment, and the weight ofthe flywheel 508 (and any parts that it drives) may be modified toprovide an initial resistance to rotation (as well as a resistance tosudden changes in the rotational speed during operation) due to theinertia of the parts.

As best shown in FIGS. 9 and 10A, the flywheel 508 includes a flywheelgear 902 that fits into a corresponding geared track 904 located in acavity on the clutch lever 612. FIG. 10A shows the clutch lever 612 andthe expanding clutch 610 with the clutch mount 614 removed. The flywheel508 and its gear 902 rotate in a generally counter-clockwise directionin the views of FIGS. 9 and 10A. Rotation of the flywheel 508 and itsgear 902 tends to pivot the clutch lever 612 about its pin 624, asindicated by arrow D1. This pivoting torque applies a force F1 againstthe expanding clutch 610 that tends to opens the expanding clutch 610,as indicated by arrow D2. As the clutch 610 expands, its diameterincreases, eventually causing the expanding clutch 610 to contract andexert pressure against the interior wall of the drum 608. The length ofthe geared track 904 is selected such that the expanding clutch 610contacts the inner wall of the drum 608 before the flywheel gear 902reaches the end of the track 904.

It will be appreciated that the expanding clutch 610 may, because of theresilient nature of the material from which it is made (plastic, forexample), provide some resistance to being expanded (this is referred toherein as the expansion resistance). If the expansion resistance isgreat enough, the torque applied by the flywheel gear 902 to the gearedtrack 904 may not generate a sufficient expansion force F1 to expand theexpanding clutch 610 into contact with the drum 608. In other instances,the expansion resistance may be very low, so that virtually nosubstantial amount of torque is required to expand the expanding clutch610. For example, the flywheel gear 902 may be able to expand theexpanding clutch 610 by applying about 1/100th of the total amount oftorque that the clutch transfers.

It will also be appreciated that the magnitude of the expansion force F1may be limited if the clutch mount 614 begins to rotate. This situationmay occur if the inertia and frictional resistance of the clutch mount614 (the clutch mount's “resistance torque”) is relatively low. Theclutch mount's resistance torque will depend on its inertia and rotatingfriction, as well as the inertia and rotating friction of any parts towhich it is attached. As explained below, the clutch mount 614 isnormally attached to the brushroll 102 and various other parts, all ofwhich increase the clutch mount's resistance torque by inertia and anyfriction between these parts and their surroundings (such as contactbetween the brushroll 102 and a surface to be cleaned) or between theseparts and each other (such as friction in a bearing). If the clutchmount's resistance torque is low enough, the torque applied by theflywheel gear 902 to the clutch lever 612 may begin to rotate the clutchmount 614 before the expanding clutch expands to contact the inner wallof the drum 608. In such a case, the amount of torque that can betransmitted to the clutch mount 614 is limited by the frictional contactbetween the drum 608 and the flywheel 508.

Where the expansion resistance of the expanding clutch 610 is lowenough, and the resistance torque of the clutch mount 614 is highenough, the flywheel gear 902 will rotate the clutch lever 612 andexpand the expanding clutch 610 as described above. Contact and pressurebetween the expanding clutch 610 and the drum 608 generate friction, andtransmits torque directly from the drum 608 to the expanding clutch 610.In the shown embodiment, the amount of leverage that the clutch lever612 applies to expand the expanding clutch 610 (and the amount of forceapplied to press the expanding clutch 610 into contact with the drum608) increases as the clutch mount's 614 resistance to rotationincreases. This is because the clutch lever pivots on mounting pin 624,which is installed in the clutch mount 614, and forces that resistrotation of the clutch mount 614 are transmitted through the mountingpin 624 in a manner that is favorable to amplify the expanding force.The use of this feature allows the expanding clutch 610 to be engagedwith relatively force and react quickly to fluctuations in the driveresistance. Thus, it can be said that the shown expanding clutch 610 isa self-adjusting clutch that increases the transmitted torque asrotational resistance of the load (i.e., the clutch mount 614 andeverything driven by it) increases. Since the rotational resistance ofthe clutch mount 614 is a function of both friction and inertia, theself-adjusting expanding clutch 610 will tend to expand and transmitgreater torque whenever the load encounters greater friction (e.g., whenthe brushroll 102 contacts a thick carpet), and whenever there is a highdifferential inertia between the parts (e.g., when the brushroll 102 isstill or rotating relatively slowly). Conversely, if the loadexperiences a condition in which it tends to overrun the expandingclutch 610 -such as when power to the motor 104 is terminated and thebrushroll 102 continues to rotate by inertia—the self-adjustingexpanding clutch 610 may release engagement with the drum 608 andtransmit little or no torque to the load. In addition, the rate at whichthe brushroll 102 can accelerate (either during startup of during speedfluctuations, may be limited by the rate at which the flywheel 508 canaccelerate via its contact with the drum 608. In one embodiment, theexpanding clutch 610 may be self-adjusting to the point that it isself-locking, so that no amount of drive resistance can overcome thefriction generated between the expanding clutch 610 and the drum 608.

The operation of the expanding clutch 610 in this manner is illustratedin FIGS. 10B and 10C, which show the expanding clutch 610 in thedisengaged and engaged position, respectively. These figures are shownfrom the opposite side as FIG. 10A, and thus the rotations are reversedin these views. As will be appreciated, it may be desirable to uselubricants, such as natural or synthetic oils or greases, lubricatedcoatings or layers, or low-friction/low-wear materials, on the expandingclutch 610, flywheel 508, as well as any other parts that engage infrictional contact, to help prevent excessive wear.

The exemplary drive clutch mechanism may be disengaged by operating thesolenoid 201 or other disengagement mechanism. The solenoid 201 or otherdisengagement mechanism may have a manual control to allow the user toengage and disengage the drive clutch at will. The solenoid 201 or otherdisengagement mechanism also may have an automatic control that engagesand disengages the drive clutch during particular circumstances, such aswhen the upper portion of an upright vacuum cleaner is pivoted to theupright parked position, or when a bare floor cleaning mode is selectedon a vacuum cleaner. Such an automatic device might comprise, forexample, a micro-switch that activates the solenoid 201, or a mechanicaloverride mechanism (such as a cam or pushrod) that presses against thelever 502, when the vacuum cleaner housing is moved to the uprightposition. As noted above, the solenoid shaft 504 presses thedisengagement lever 502, which rotates on its pivots 503 and moves theflywheel 508 out of contact with the drum 608. When the flywheel 508 isdisengaged from the drum 608, it no longer applies a torque to theflywheel gear 902. When this happens, expanding clutch's expansionresistance tends to contact the expanding clutch 610 and pull it awayfrom contact with the drum 608. In addition, a weight 620 may beprovided on the clutch lever 612 to assist with disengaging theexpanding clutch 610. The weight 620 is located on the clutch lever 612where centrifugal force presses the weight 620 opposite the rotationimparted by the flywheel gear 902. As a result, the weight 620 resistsengagement of the expanding clutch 610, and causes the clutch lever 612to retract to the disengaged position once the torque from the flywheelgear 902 is terminated. Having terminated frictional contact between theflywheel 508 and the drum 608 and the expanding clutch 610 and the drum608, torque is no longer transmitted through the clutch assembly 100 tothe clutch output gear 140. Thus, the shaft 602 and brushroll 102 maydecelerate and eventually stop rotating. Even when the drive clutch isdisengaged, however, the clutch input gear 130 and the drum 608 maycontinue to rotate for as long as the motor 104 operates. It will beappreciated that the weight 620 may, in other embodiments, be omitted,relocated or replaced by other mechanisms, such as a spring that tendsto pivot the clutch lever 612 against the force applied by the flywheelgear 902.

In the exemplary embodiment, the expanding clutch 610 is able totransmit significantly more torque between the drum 608 and the clutchmount 614 than the frictional contact between the flywheel 508 and drum608. This difference in torque capacity may be attributed to the size ofthe contacting surfaces, as well as the mechanical design of the parts.For example, the expanding clutch operates as a drum-type clutch and hasa relatively large contact area, whereas the flywheel-to-drum contactsurfaces operate as a disk clutch having a relatively small contactarea. Thus, the present exemplary embodiment provides a two-clutchsystem. Under normal conditions, the first clutch (the flywheel/drumsystem) may have insufficient torque transferring capability to operatethe brushroll 102, and is instead used to engage the expanding clutch610 in a controlled manner. Alternatively, if the system is modifiedaccordingly, the first clutch may be able to operate the brushroll 102under relatively low load conditions. If desired, the shapes, sizes andkinds of these two clutch systems may be modified to obtain differentdifferences in their torque transferring capabilities. For example, thefrictional contact between the drum 608 and flywheel 508 may be modifiedby adjusting the force applied by the spring 622 or changing thecoefficient of friction between the parts. Changing the weight of theflywheel weight 506 can also adjust how quickly the flywheel acceleratesin response to contact with the drum 608. Similar adjustments may bemade to the expanding clutch 610. For example, the pins 626, 628 used toexpand the expanding clutch 610 may be positioned in angled slots thatapply a radial force to increase frictional contact with the drum 608,or the shape of the clutch lever 612 may be modified to apply more orless leverage to expand the expanding clutch 610. Other modificationswill be understood by persons of ordinary skill in the art in view ofthe present disclosure.

The configuration of clutches in the foregoing embodiment has been foundto provide a relatively smooth transfer of torque from the motor outputgear 120 to the brushroll 102. This smooth transfer of torque lessensthe maximum torque differential between the motor output gear 120 andbrushroll 102. This is particularly the case when comparing theforegoing embodiment to direct-drive devices that drive the brushroll102 directly by the motor output gear 120 through a belt. Suchdirect-drive devices, which are in widespread use, typically use motorsthat generate their maximum torque at zero revolutions per minute. This,combined with the fact that the brushroll is not rotating at startup andmay have frictional resistance to rotation, leads to a relatively hightorque differential between the motor and the brushroll that must beconveyed through the driveline. While the overload mechanism describedabove or elsewhere herein can be modified to accommodate this hightorque, it may take a sufficiently high differential torque to disengagethe overload mechanism. This may be suitable in some instances, such aswhere the motor has relatively low power, but may not be suitable inother instances. Thus, a clutch engagement mechanism such as the onedescribed above, which reduces the maximum torque differential that canbe transmitted across the overload mechanism by providing a relativelylow-torque or graduated-torque “soft” start, may be used in conjunctionwith an overload mechanism that will disengage if a relatively lowtorque differential is applied to it.

As noted above, torque transmitted to the clutch mount 614 may beconveyed to the brushroll 102 via an overload mechanism. The overloadmechanism terminates the transfer of torque from the motor output gear120 to the brushroll 102 when an excessive amount of torque is appliedto the overload mechanism. Referring to FIGS. 11 and 12, in the presentembodiment, the overload mechanism may include an overload cog 616 andan overload spring 618.

The overload spring is connected to the clutch mount 614 on the sideopposite the clutch lever 612. Thus, in this embodiment, the clutchmount 614 also acts as an overload spring mount. As shown, the overloadspring may be attached at a mounting bracket 1104. As shown, theoverload spring 618 may be wrapped around a pin 1112 that passes throughthe bracket 1104, and allows the overload spring 618 to pivot if nototherwise constrained from moving. In other embodiments, other mountingmethods may be used. For example, an end of the overload spring 618 maybe pressed into a groove or channel on the surface of the clutch mount614, providing a rigid connection point, but still allowing the overloadspring 618 to flex during normal operation of the clutch and in overloadconditions, as described below. The overload spring 618 may be made fromhardened steel or any suitable alternative material. The shape of theoverload spring 618 may be modified to avoid sharp bends that mightstretch over time or create weak points in the material structure.

The overload spring 618 wraps around the overload cog 616 and is shapedto transfer torque from the clutch mount 614 to the overload cog 616 tothereby rotate the overload cog 616. The overload cog 616 is rigidlymounted to the shaft 602, and directly transfers torque and rotation tothe clutch output gear 140, which is also rigidly mounted to the shaft602. The overload cog 616 may be rigidly mounted to the shaft 602 by anysuitable structure. For example, as shown in a pin 1106 may pass throughthe shaft of 602 and engage a slot 1108 on the face of the overload cog616. In the shown exemplary embodiment, the overload cog 616 is notconnected only to the shaft 602 and clutch output gear 140, but in otherembodiments it may be attached to one or more other parts.

The exemplary overload cog 616 is generally circular and has a series ofteeth 617 or other protrusions that extending radially outward. Inaccordance with an exemplary embodiment, the overload cog 616 may havethree teeth 617. The overload spring 618 is shaped similarly to theoverload cog 616, so that it engages the teeth 617 to transfer of torquethrough the overload cog 616 to the shaft 602. For example, in the shownembodiment, the overload spring 618 has a generally circular shape withrounded lobes 619 that fit over the teeth 617 when the overload spring618 and overload cog 616 are in certain orientations with respect to oneanother. Stated differently, the overload cog 616 has first portionsthat extend a first distance from its rotating axis (e.g., the circularportions), and second portions that extend a second distance from therotating axis (e.g., the teeth 617), and the overload spring 618 isconfigured to wrap around the overload cog 616 and have first portionsthat conform generally to the first portions of the overload cog 616,and second portions that conform generally to the second portions of theoverload cog 616. While it could be possible to have the overload spring618 conform more precisely to the shape of the overload cog 616, it hasbeen found that it is not necessary to make these two parts matchprecisely, and doing so might, in some circumstances, create undesirablestress risers in the parts.

In normal operation the overload spring 618 is wrapped around theoverload cog 616, and the rounded lobes 619 fit over the teeth 617. Whena torque is applied to rotate the clutch mount 614 (such rotation iscounterclockwise in FIGS. 11 and 12), the clutch mount 614 pulls theoverload spring 618 (via pin 1112) to rotate in unison with the clutchmount 614. Contact between the overload spring 618 and overload cog 616transmits the drive torque to, and thereby rotates, the overload cog616. The overload spring's 618 spring tension (i.e., its resistance todeformation) maintains the overload spring's 618 contact with theoverload cog 616 in the shown engaged, torque-transferring orientation.The parts will remain in this orientation with respect to one anotherand continue to rotate together until the drive torque transmittedthrough the clutch mount 614 is terminated, or the overload cog 616encounters sufficient rotational resistance (resistance torque) that theoverload spring 618 disengages from the overload cog 616. Suchresistance torque can be generated, for example, if the brushroll 102encounters high resistance to rotation or is prevented from rotating, asmay occur if a foreign object becomes entangled in the brushroll. Theamount of torque that can be transmitted from the overload spring 618 tothe overload cog 616 is referred to herein as the overload clutch'storque rating.

The overload clutch's torque rating may be determined primarily by theshapes of the parts and the spring's resistance to deformation. Forexample, if the overload cog 616 has relatively angular teeth 617 andthe lobes 619 on the overload spring 618 conform closely to the teeth617, the mechanical engagement between the two may require transferrelatively more torque than if softly rounded teeth 617 orloosely-conforming lobes 619 are used. Also, if the overload spring 618is made from a more resilient or thinner material, the torque rating ofthe overload clutch may be reduced. In addition, other embodiments mayuse other shapes to provide releasable engagement between the overloadcog 616 and the overload spring 618. For example, the overload cog 616may have depressions into which inwardly-extending lobes on the overloadspring 618 fit to provide releasable, torque-transferring engagementbetween these parts. In other embodiments, the overload spring 618 maybe located within a hollow overload cog 616, and in still otherembodiments, the overload spring 618 may be mounted to the shaft 602 torotate therewith, and the overload cog 616 may be mounted to the clutchmount 614 to rotate therewith. These and other variations will beapparent from the present disclosure, and a person of ordinary skill inthe art will be able to develop appropriate configurations anddimensions for these parts in view of the present disclosure withoutundue experimentation.

When the overload clutch's torque rating is exceeded, the overloadspring 618 will continue to rotate with the clutch mount 614, but theoverload cog 616 will either stop or rotate at a different, slowerspeed. In such circumstances, the lobes 619 disengage from the teeth617, and the portions of the overload spring 618 between the lobes 619will move into contact with the teeth 617. When this occurs, theoverload spring 618 is deformed and generally increases in diameter topass over the teeth 617. In this state, the overload spring 618 maystill tend to wrap around and contact the overload cog 616, in whichcase these two parts will have insubstantial contact one another duringoverload conditions, and such contact would not be sufficient togenerate a torque that could damage the agitator or objects that itmight contact. For example, such contact might be sufficient to rotatethe agitator when it is lifted free of the surface being cleaned andotherwise not obstructed, but not to rotate the agitator if it islightly contacted by the user's fingers. This may be desirable becausecontact between the parts may provide an audible sound to signal theoperator that an overload has occurred. Under this scenario, theoverload spring 618 may optionally also be able to reengage the overloadclutch 616 if the resistance torque decreases. For example, the operatormay momentarily pass the vacuum cleaner brushroll 102 over an object(such as frayed strand from a carpet) that generates sufficientresistance to exceed the torque rating and disengage the overload spring618, but then pull the brushroll 102 free of the object to reduce therotating resistance, at which time the overload spring 618 may reengagethe overload cog.

While the foregoing arrangement is possible, in other embodiments it maybe desirable to prevent the overload spring 618 from reengaging theoverload cog 616 until the user terminates drive to the overload clutch.For example, preventing automatic reengagement of the overload clutchmay be desirable to limit the likelihood that the operator will besurprised by a sudden resumption in the brushroll's operation, and itmay be desirable to prevent the overload spring 618 from wearing on theoverload cog 616 during overload. In the shown exemplary embodiment, amechanism may be provided to help hold the overload spring 618 away fromthe overload cog 616 during overload conditions. For example,centrifugal force may be used to hold the overload spring 618 away fromthe overload cog 616 until the clutch mount 614 stops rotating or slowssignificantly. To further help prevent automatic reengagement, theexpanding clutch 610 may remain pressed against the drum 608 even afterthe overload clutch disengages, to provide a high torque differentialthat can not be overcome until the parts come to rest or otherwise matchspeeds.

As noted above, during overload conditions, the overload spring 618disengages from the overload cog 616. When this occurs, overload spring618 is free to pivot away from the overload cog 616, and centrifugalforce will tend to expand the overload spring 618 radially outward andaway from the overload cog 616, such as shown in FIG. 12. The overloadspring 618 may be weighted or have sufficient weight of its own thatcentrifugal force holds the overload spring 618 in the disengagedposition. In addition a pawl 1102 may be pivotally mounted to the clutchmount 614, such as at the mounting bracket 1104, to contribute itsweight (and resulting centrifugal force) to help press the overloadspring 618 in the expanded, disengaged position. The pawl 1102 may bemounted on the same bracket 1104 as the overload spring 618, orelsewhere. In the shown embodiment, the pawl 1104 may be pivotallymounted to the bracket 1104 by the pin 1112, and the end of the overloadspring 618 may tightly wrap around the pivoting end of the pawl 1102 tothereby pivotally mount the overload spring 618 to the clutch mount 614.

It will be appreciated that other additional weights or springs may beused to help hold the overload spring 618 in the disengaged position.For example, a weight may be provided along the length or at the freeend of the overload spring 618. As another example, a weight that slideson a sliding radial track may be positioned inward of a portion of theoverload spring 618 to apply centrifugal force to the overload spring618. A helper spring may also be provided to press the overload spring618 outward. A helper spring may also be provided to press the overloadspring 618 inward, if it is not desired to fully disengage the overloadspring 618 during overload conditions.

As shown in FIG. 12, during overload conditions, the overload spring 618is pressed radially outward by its own weight and the weight of the pawl1102. One or more walls or other blocking structures 1116 may be locatedon the clutch mount 614 to control the outward movement of the overloadspring 618. Such blocking structures 1116 may also provide a fulcrumpoint that cooperates with centrifugal force on the overload spring 618to bend the overload spring 618 so that it clears the overload cog 616.

As shown in FIG. 11, the pawl 1102 may also (or alternatively) beprovided to act as a back brake that prevents the overload cog 616 fromrotating faster than the clutch mount 614. In this exemplary embodiment,during normal (i.e., non-overload) operating conditions, the pawl 1102is pivoted so that its free end 1102′ engages one of the overload cogteeth 617. The free end 1102′ of the pawl 1102 and the cog teeth 617 areshaped such that the teeth 617 can not rotate past the pawl 1102. Thus,the pawl 1102 prevents the overload cog 616 from rotating faster thanthe clutch mount 614.

Such a configuration may be desirable to prevent the brushroll 102 fromcontinuing to rotate even after the motor 104 has been turned off, orfrom rotating faster than the motor 104 during normal operation when thebrushroll 102 experiences a momentary drop in rotating resistance or isaccelerated by elastic tension developed in the brushroll belt 108. Forexample, in the exemplary embodiment, when the motor 104 is turned offwhen the drive and overload clutches are still engaged, the brushroll102 may tend, due to its rotating inertia, to continue rotating. Withoutthe pawl 1102 or other back brake, the brushroll's inertia may betransmitted to the overload spring 618 through the overload cog 616,possibly disengaging the overload clutch and allowing the brushroll 102to continue spinning. With the exemplary back brake, however, the pawl1102 transmits forces caused by rotating inertia directly to the clutchmount 614 and back through the drive clutch. If the inertial forces aregreat enough, the brushroll 102 may force the drive clutch to overrunthe motor, but friction between the drive clutch elements, such asbetween the drum 608 and flywheel 508 will rapidly dissipate thisenergy. While the pawl 1102 is shown as one exemplary embodiment, otherback brake or overrun prevention mechanisms may be used instead of thepawl 1102; for example, the pawl 1102 may be formed by an extension ofthe overload spring 618 that is folded back to face the overload cogteeth 617.

Other features may be provided in various embodiments to increase thetorque rating of the overload clutch. For example, the free end of theoverload spring 618 (i.e., the end opposite the end that is connected tothe clutch mount 614) may include a curled end 1114, such as the showncircular knob, that fits between the overload cog 616 and a wall portion1110 formed on the clutch mount 614. The curled end 1114 is large enoughthat it can not fit between the wall portion 1110 and the overload cogteeth 617 unless it is deformed, but small enough that it can freely fitbetween the remainder of the overload cog 616 and the wall 1110 withoutbeing deformed. During normal operation (i.e., when the overload clutchis engaged), the curled end 1114 fits between the wall portion 1110 andthe overload cog 616. In this embodiment, the overload spring 618 willcontinue to transmit torque to the overload cog 616 until there issufficient resistance to compress the curled end 1114 so that it canpass between the clutch mount wall 1110 and the adjacent overload cogtooth 617. The curled end 1114 preferably is generally circular todistribute the compression force across the material and resistpermanent deformations, but it may be V-shaped or have other shapes.Once disengaged, the overload spring 618 is pressed by centrifugal forceaway from the overload cog 616. Once the clutch mount 614 substantiallystops rotating, the overload spring 618 returns to its contractedposition against the overload cog 616. Once this happens, the curled end1114 will be reseated between the wall 1110 and the overload cog 616 asthe two parts rotate relative to one another just prior to reengaging.Thus, the shown exemplary embodiment prevents reengagement of theoverload spring 618 and overload cog 616 until the clutch mount 614 andoverload cog 616 substantially stop rotating.

When used with the drive clutch mechanism of FIGS. 6-10C, the foregoingoverload clutch may automatically disengage the expanding clutch 610when the overload clutch enters the overload state shown in FIG. 12.When the overload spring 618 disengages from the overload cog 616,clutch mount 614 can freely rotate and may provide little resistance tothe torque provided by the flywheel gear 902. Under these conditions,the clutch lever pin 624 may no longer provide a fulcrum point throughwhich the flywheel gear 902 can generate force to expand the overloadclutch 610. When this happens, the expansion resistance of the expandingclutch 610 (and the clutch lever weight 620, if provided) may exertsufficient force to return the expanding clutch 610 to the disengagedposition. Alternatively, the expansion resistance of the expandingclutch 610 may be insufficient to disengaged the expanding clutch 610from the drum 608, even when the overload clutch enters the overloadstate, in which case the expanding clutch 610 may continue to engage anddrive the drum 608 until the flywheel is disengaged from the drum 608.

While the foregoing overload clutch mechanism may be used independently,it also may be used with a drive clutch, such as the soft-start driveclutch described above. It has been found that the combination of thefeatures shown in FIGS. 1-12 can provide certain benefits andsimultaneously address numerous criteria desired of a brushroll drivemechanism. For example, the drive clutch provides a low accelerationtorque that allows the use of an overload clutch having a relatively lowtorque rating. This allows the overload mechanism to disengage virtuallyinstantaneously upon sensing a relatively low force, but at the sametime does not deactivate during normal drive torque fluctuations. Inaddition, the use of a first drive clutch that is used to engage asecond drive clutch (particularly a second drive clutch that isself-adjusting) allows the first drive clutch to have a relatively lightengagement spring. This feature facilitates the use of a simpleengagement/disengagement mechanism, and requires relatively little forceto operate the drive clutch. Thus, the shown embodiment can be operatedwith relative ease either manually or by a suitable electromechanicaldevice (e.g., a solenoid). The embodiment described above also mayprovide overload protection that terminates all or virtually all drivetorque through the overload clutch during overload conditions, andrequires termination of drive torque through the drive clutch mechanismbefore the brushroll can be restarted, thus protecting againstaccidental restarts. Once the overload clutch is activated, the usermust either turn off the motor or disengage the drive clutch before theoverload clutch will reset. Still another benefit that may be realizedfrom the above embodiment is a significant reduction in brushroll speedas a result of the two-stages of gear reduction provided through theclutch assembly.

While the foregoing combination of drive and overload clutch mechanismsmay be desirable in some instances, alternative embodiments may replacethe clutch and/or overload mechanisms with alternative structures thatmay provide the same or different functions. For example, the driveclutch mechanism, as described above, may be replaced without alteringthe overload clutch mechanism and vice versa. Further, the arrangementof the clutch assembly 100 may be altered from the relatively compactstructure as described above, to an expanded arrangement having thedrive and overload clutch mechanisms spatially separated along a commonshaft. Such mechanisms also may be mounted on separate shafts orprovided as independent modules. Thus, as should be appreciated, theembodiments presented herein may be combined in any manner and even usedindependently of one another. For example, the clutch mechanism of thefirst embodiment may be used without the overload mechanism and viceversa. It will also be understood that the various parts can berearranged in inverted or reversed relationships. For example, the drumand expanding clutch configuration may be replaced by a spindle andcontracting clutch, or the initial clutch may be a drum-type clutch thatis adapted to fully engage a disk-type clutch as the main drive clutch.In other embodiments, the overload clutch may be located “upstream” ofthe drive clutch mechanism (that is, between the motor and the driveclutch), as opposed to being “downstream” as in the above-describedembodiment. These and other variations will be understood by persons ofordinary skill in the art.

Another embodiment of a drive clutch engagement mechanism is illustratedin FIGS. 13A-13B. Like the foregoing embodiment, this embodiment uses anexpanding clutch to engage a drive shaft to a drum but replaces theflywheel and clutch lever arrangement with a pin and collar structure.This arrangement is shown in the disengaged position in FIG. 13A, and inthe engaged position in FIG. 13B. In this embodiment, a flywheel (notshown) such as the one described above has one or more pins 1302 thatextend from the face of the flywheel. The pins 1302 fit in correspondingnotches 1304 in a collar 1306. The collar 1306 generally surrounds ashaft 1308, but includes a slot 1310 to accommodate a crossbar 1312 thatextends radially from the shaft 1308. An expanding clutch 1314 surroundsthe collar 1306, and has a gap that accommodates the crossbar 1312, asshown in FIG. 13A. On one side of the slot 1310, the collar 1306 has apoint 1316 that abuts one side of the crossbar 1312, and an extension1318 that fits between the crossbar 1312 and the expanding clutch 1314.A drum 1320 surrounds the expanding clutch 1314 and collar 1306. Thedrum 1320 is driven by a motor (not shown) in a counterclockwisedirection as shown by the arrow.

In the disengaged position, the collar 1306 is positioned such that theextension 1318 is generally adjacent the crossbar 1312 and the expandingclutch 1314 is elastically contracted away from the drum's innersurface. If necessary, a spring (not shown) or other device may beprovided to bias the parts in this position. For example, the slot 1310may be configured to require some amount of elastic deformation to movefrom the disengaged position. When it is desired to engage the clutch,the flywheel (not shown) is moved into engagement with the drum 1320,such as in the embodiment described above. Upon such engagement,friction between the drum 1320 and the flywheel rotates the pins 1302about the shaft 1308 in a counterclockwise direction. Movement of thepins 1302 rotates the collar 1306 about the shaft 1308, as shown in FIG.13B. In this position, the point 1316 on the slot (which may comprise arectilinear or curved surface) contacts the side of the crossbar 1312,and acts as a fulcrum about which the collar 1306 rotates. As the collar1306 rotates, the extension 1318 moves away from the crossbar 1312 andexpands the expanding clutch 1314 by opening the gap in the clutchsurface. As the expanding clutch 1314 expands, it contacts the innersurface of the drum and thereby is driven directly by the drum 1320. Aswith the above embodiment, the clutch may be disengaged by separatingthe flywheel from the drum.

Referring now to FIG. 14, another exemplary embodiment may providealternative drive clutch and overload clutch mechanisms that arearranged axially upon a torque transmission shaft. The embodiment ofFIG. 14 comprises a clutch assembly 1400 having a cone clutch mechanismthat is used as a drive clutch, and a magnetic coupling that is used asan overload clutch. It is known in the art that cone shaped clutchmechanisms may provide efficient transfer of power. It is also knownthat magnets may provide a way to couple two objects, such as rotatingdisks, together, through an attractive magnetic force, with no contactbetween the objects. The attractive magnetic force must be strong enoughto allow the objects to couple and rotate together to transfer therequired torque loading. Such magnetic coupling may be used as anoverload mechanism for the clutch assembly.

As shown, the exemplary clutch assembly 1400 may have a clutchengagement member 1402, a first cone 1404, a second cone 1406, a thirdcone 1408, a shaft 1410, and an overload drive plate 1414, and an outputpulley 1416. The shaft 1410 may run the length of the clutch assembly1400 and be supported by bearings 1412 a and 1412 b. In this embodiment,the third cone 1408 and the overload drive plate 1414 may be fixed tothe shaft 1410 to rotate therewith. A spring (not shown) may be locatedbetween the first cone 1401 and the overload drive plate 1414 to biasthe first cone 1404 into engagement with the second cone 1408, tothereby force it into engagement with the third cone 1408. Theengagement member 1402 is provided to pull the first cone 1404 againstthe bias of the spring and out of disengagement. The engagement member1402 may be automatically or manually operated, and in otherembodiments, the first cone 1404 may be biased out of engagement withthe second cone 1406, in which case the engagement member 1402 would beoperated to engage the drive clutch, rather than disengage it.

As shown, the second cone 1406 may include a drive gear 1406′ on itsexterior surface. The drive gear 1406′ is driven by a motor through abelt or other suitable drive mechanism. Upon engagement, the first cone1404 presses the second cone 1406 into the third cone 1408, and theconical surfaces between the parts provide frictional engagement thatlocks the parts together. When fully engaged, the motor drives the thirdcone 1408 to rotate the shaft 1410. The second cone 1406 is not coupledto the shaft 1410, such that when the clutch is not engaged, the secondcone 1406 may rotate freely around the shaft 1410 while the motor 104 isrunning. Of course, other kinds of surfaces may be used to frictionallyengage these parts. For example, the conical surfaces may be replaced bydisk-like surfaces.

The shaft 1410 drives the overload drive plate 1414, which is fixed tothe shaft 1410 to rotate therewith. The overload drive plate 1414includes one or more magnets 1418 that face the output pulley 1416. Theoutput pulley 1416 includes its own magnets 1420, which are arranged tocontact the other magnets 1418 to provide a drive coupling between theseparts, as known in the art. The output pulley 1416 is freely rotatableon the shaft 1410, and the amount of torque that may be transmitted fromthe overload drive plate 1414 to the output pulley 1416 is limited bythe magnetic properties of the magnets 1418, 1420. The output pulley1416 includes a gear surface 1416′ or other surface adapted to connectto and drive a brushroll or other downstream driven part through a belt,gears or the like.

An arrangement of magnets may be used with the magnetic overloadmechanism described above. For example, the magnets on one part may allhave their north poles facing the other part, and the other part maypresent only the south poles of its magnets. Alternatively, the polesmay be oriented to alternate or provide other patterns. As anotheralternative, one or more of the magnets may be replaced by bars ofmaterial that are not magnetized but are attracted to the magnets thatremain in the parts. Various magnetic overload configurations aredisclosed in various patents discussed above, which are incorporatedherein by reference.

It should be appreciated that the magnetic overload coupling may havedifferent configurations to improve torque transfer and overloadresponse. For example, the embedded magnets may be mounted on angledsurfaces such that the attractive force is at an angle to the shaft1410, and some amount of axial movement must be accomplished before themagnets fully disengage. FIG. 15 depicts such an alternative embodimentof the overload drive plate 1414 and output pulley 1416. In thisembodiment, the overload drive plate 1414 has angled faces in which themagnets 1418 are embedded. In FIG. 15, the overload drive plate 1414rotates such that the side facing the viewer moves upwards. Thus, themagnets 1418, 1420 operate in tension, with magnets 1418 pulling magnets1420 to follow the rotation of the overload drive plate 1414. When themagnets 1418, 1420 break contact, the overload drive plate 1414 andoutput pulley 1416 rotate relative to one another, and ramps 1502 may beprovided to facilitate relative axial movement of the parts. Inaddition, one or both of the overload drive plate 1414 and output pulley1416 may be axially slideable on the shaft 1410 to allow such movement.A spring or other resilient member may be used to bias the overloaddrive plate 1414 and output pulley 1416 together to reestablish contact,but such movement may be provided by the magnets 1418, 1420 instead. Ofcourse, the opposite rotation may be used instead, in which the magnets1418, 1420 tend to press together in operation.

A magnetic overload clutch also may be used with other embodiments ofdrive clutches. For example, the embodiments of FIGS. 14 or 15 may beused with the drive clutch described in FIGS. 6 through 10A. In anotherembodiment, shown in FIGS. 16A-C, a magnetic overload mechanism isintegrated into the expanding clutch to disengage it when the torquetransmitted from the drum to the expanding clutch exceeds a thresholdvalue.

The embodiment of FIGS. 16A-C includes a drum 1600, expanding clutch1602, clutch mount 1604, clutch lever 1606, flywheel gear 1608 andflywheel (not shown) generally like those described above with referenceto FIGS. 6-10A. As before, the expanding clutch 1602 is operated bycontacting the flywheel against the drum 1600 to thereby generate aforce to pivot the clutch lever 1606 and expand the expanding clutch1602 into engagement with the drum 1600. These parts are shown in thedisengaged position in FIG. 16A, and in the engaged position in FIG.16B. In these views, the drum 1600 rotates clockwise.

The torque applied by the drum 1600 to the expanding clutch 1602 istransmitted to the clutch mount 1604, which, in turn, is connected to abrushroll or other load, either directly or through any other suitablemechanisms. The trailing end of the expanding clutch 1602 (i.e., the endan imaginary point on the drum would pass over last as it rotates) isattached to the clutch mount 1604 by one or more magnets 1610, 1612.During normal operation, the magnets 1610, 1612 hold the end of theexpanding clutch 1602 and allow it to be expanded into contact with thedrum 1600. The magnets 1610, 1612 transfer at least some of the torquethat the drum 1600 imparts to the expanding clutch 1602 to the clutchmount 1604, to thereby rotate the clutch mount 1604. When the clutchmount 1604 encounters a rotational resistance torque, such as when thebrushroll becomes obstructed or stops, the magnets 1610, 1612 maydisengage, allowing the expanding clutch 1602 to contract and move outof engagement with the drum 1600. This overload condition is shown inFIG. 16C. Thus, the magnets 1610, 1612 act as an overload clutchmechanism. The strengths and orientations of the magnets 1610, 1612 may,of course, be modified to regulate the torque rating of the overloadclutch. In addition, a counterweight 1616 may be attached to the clutchmount 1604 to help balance the weight of the magnets 1610, 1612 toprevent excessive vibrations.

In the embodiment of FIGS. 16A-C, the clutch mount 1604 does notdisengage from the brushroll during an overload condition. Thus, theflywheel gear 1608 still continues to apply a torque to rotate theclutch lever 1606 and rotate the clutch mount 1604. At the same time,this torque may keep the clutch lever 1606 at least partially rotatedwhich may hold the expanding clutch 1602 so that its magnets 1610 cannot reengage the magnets 1612 on the clutch mount 1604, as shown in FIG.16C. During this time, the flywheel may remain in contact with the drum1600, generating friction between the parts. As such it is preferred forthe contact surfaces between flywheel and drum 1600 to be made of aheat-resistant material. Once the flywheel is disengaged form the drum1600, the clutch lever 1604 can pivot back to its resting disengagedposition, and the magnets 1610, 1612 can reengage.

Still other overload and drive clutch devices may be used with otherembodiments. For example, as FIG. 17 discloses a wave plate clutch thatmay be used as an overload clutch in a vacuum cleaner, either on its ownor in conjunction with a drive clutch such as the ones described herein.The embodiment of FIG. 17 provides a wave plate-type clutch having afirst plate 1702 that is biased by a spring 1706 to press against asecond plate 1704. The first plate 1702 is driven by a first shaft 1708,and the second plate drives a second shaft 1710. This clutch willtransmit torque until sufficient differential loads exist to press theengaged structures out of engagement against the bias of the spring1706, as will be appreciated by persons of ordinary skill in the art.Upon clearance of the resistance torque, normal operation mayautomatically resume.

Alternatively, a clutch mechanism may use a friction forces from springlocated between two toothed wheels to transmit torque. Such anembodiment is shown in FIGS. 18A-C. In this exemplary embodiment, aclutch mechanism may have an inner wheel 1802 with a toothed profilearound the outer diameter. The inner wheel 1802 may be mounted to ashaft (not shown) by an inner hole 1806. An outer wheel 1804 surroundsthe inner wheel 1802, and has an internally-facing toothed profile,similar to that of the inner wheel 1802, around its inner diameter. Oneof the two wheels is driven by a motor, either directly or through adrive clutch or other mechanisms, and the other transmits the drivetorque to an output device, such as a brushroll. In the shownembodiment, for example, the outer wheel 1804 may be drive by expandingclutch mechanism, such as described above, such engaging the expandingclutch imparts a drive torque to the outer wheel 1804 to rotate as shownby the arrow. One or more elastic springs are located between the innerwheel 1802 and outer wheel 1804 to transfer drive torque from the outerwheel 1804 to the inner wheel 1802. For example, a number of thin, flatmetal strings or ribbons 1808 may be located between the teeth of theinner wheel 1802 and the outer wheel 1804. While three are shown, fouror other numbers of ribbons 1802 may be used.

The ribbons 1808 are shaped so that they can transfer torque from theteeth on the outer wheel 1804 to the teeth on the inner wheel 1802. Forexample, as shown, the ribbons 1808 may have a curved profile thatsimultaneously fits between one or more teeth on each wheel 1802, 1804.In normal operation, as shown in FIG. 18B, the ribbons are strong enoughto generally maintain their shape and transmit torque from the outerwheel 1804 to the inner wheel 1802. However, when the inner wheel 1802encounters sufficient resistance, the ribbons 1808 may be deform andflattened, such as shown in FIG. 18C, and thus disengage the teeth ofone or both of the wheels 1802, 1804. When this occurs, the wheels 1802,1804 can rotate relative to one another, and the inner wheel 1802 mayslow or stop. Upon clearing whatever caused the resistance on the innerwheel 1802, the ribbons 1808 return to their original shape, and normaloperation may resume.

The present disclosure describes a number of new, useful and nonobviousfeatures and combinations of features that may be used alone or togetherwith vacuum cleaners and other kinds of appliances or devices thatrequire selective torque coupling, overload protection or both. Thevarious parts and devices shown herein may be made using any suitabletechnology, such as machining, casting, injection molding, sintering,and the like, and may comprise any suitable material, such as iron,plastic (ABS, PA, reinforced, or other kinds of plastic), aluminum,steel, and so on. The selection of the manufacturing method and materialwill depend on typical engineering factors and will be appreciated bythe person of ordinary skill in the art without further explanationherein. In addition, the various parts provided in the embodimentsdescribed herein can be rearranged, such as by placing an overloadclutch between a motor and an engagement clutch, and so on. Theembodiments described herein are all exemplary, and are not intended tolimit the scope of the inventions in any way. It will be appreciatedthat the inventions described herein can be modified and adapted invarious ways and for different uses. For example, embodiments of theinvention may be used to drive motorized wheels on a vacuum cleaner, orto drive other household or industrial appliances or equipment thatrequire selective application of drive torque to one or more movingparts or overload protection features. All such modifications andadaptations are included in the scope of this disclosure and theappended claims.

1. A clutch assembly for a vacuum cleaner, the clutch assemblycomprising: a clutch assembly input adapted to be driven by a motor; aclutch assembly output adapted to drive an agitator; a starter clutchmoveable between an engaged starter clutch position in which the starterclutch receives a first drive torque from the clutch assembly input, anda disengaged starter clutch position in which the starter clutchreceives substantially no torque directly from the clutch assemblyinput; and a drive clutch moveable between an engaged drive clutchposition in which the drive clutch receives a second drive torque fromthe clutch assembly input, and a disengaged drive clutch position inwhich the drive clutch receives substantially no torque directly fromthe clutch assembly input; wherein the starter clutch is coupled to thedrive clutch such that the starter clutch, when in the engaged starterclutch position, can transmit the first drive torque to the drive clutchto move the drive clutch into the engaged drive clutch position; andwherein the drive clutch is coupled to the clutch assembly output suchthat the drive clutch, when in the engaged drive clutch position, cantransmit the second drive torque to the clutch assembly output.
 2. Theclutch assembly of claim 1, wherein: the clutch assembly input comprisesa drum having a side drum surface; and the starter clutch engages theside drum surface in the engaged starter clutch position, and does notengage the side drum surface in the disengaged starter clutch position.3. The clutch assembly of claim 2, wherein: the drum further comprisesan inner drum surface; and the drive clutch engages the inner drumsurface in the engaged drive clutch position, and does not engage theinner drum surface in the disengaged drive clutch position.
 4. Theclutch assembly of claim 1, wherein: the clutch assembly input comprisesa drum having an inner drum surface; and the drive clutch engages theinner drum surface in the engaged drive clutch position, and does notengage the inner drum surface in the disengaged drive clutch position.5. The clutch assembly of claim 4, wherein the drive clutch comprises: aclutch mount rotatably mounted within the drum; an expanding clutchmounted to the clutch mount and movable between an expanded position inwhich the expanding clutch contacts the inner drum surface when thedrive clutch is in the engaged drive clutch position, and a contractedposition in which the expanding clutch does not substantially contactthe inner drum surface when the drive clutch is in the disengaged driveclutch position; wherein, when the drive clutch is in the engaged driveclutch position, the expanding clutch transmits the second torque fromthe drum and to the clutch mount.
 6. The clutch assembly of claim 5,wherein: the drive clutch further comprises a clutch lever pivotallymounted to the clutch mount; a first end of the expanding clutch ismounted to a first end of the clutch lever; a second end of theexpanding clutch is mounted to the clutch mount; a second end of theclutch lever is moveable from a first lever position in which theexpanding clutch is in the expanded position, and a second leverposition in which the expanding clutch is in the contracted position;and wherein the clutch lever is biased into the second lever position.7. The clutch assembly of claim 6, wherein the starter clutch applies anengagement force to bias the clutch lever towards the first leverposition when the starter clutch is in the engaged starter clutchposition.
 8. The clutch assembly of claim 1, further comprising: anoverload clutch coupled to the drive clutch such that the overloadclutch receives the second drive torque from the drive clutch when thedrive clutch is in the engaged drive clutch position, the overloadclutch being moveable between an engaged overload clutch position inwhich the overload clutch transmits the second drive torque to theclutch assembly output, and a disengaged overload clutch position inwhich the overload clutch transmits substantially none of the seconddrive torque to the clutch assembly output.
 9. The clutch assembly ofclaim 8, wherein the overload clutch comprises: an overload cog; and anoverload spring; wherein, when the overload clutch is in the engagedoverload clutch position the overload spring interfaces with theoverload cog to transmit the second drive torque through the overloadclutch, and when the overload clutch is in the disengaged overloadclutch position the overload spring deforms sufficiently to prevent thetransmission of at least a substantial amount of the drive torquethrough the overload clutch.
 10. The clutch assembly of claim 9, whereinthe overload spring is connected to the drive clutch and adapted torotate therewith and the overload cog is connected to the clutchassembly output and adapted to rotate therewith.
 11. The clutch assemblyof claim 9, wherein the overload spring moves substantially out ofcontact with the overload cog when the overload clutch is in thedisengaged overload clutch position.
 12. The clutch assembly of claim 9,wherein the overload clutch remains in the disengaged overload clutchposition until the starter clutch is moved to the disengaged starterclutch position.
 13. The clutch assembly of claim 9, wherein the driveclutch is biased into the disengaged drive clutch position when theoverload clutch is in the disengaged overload clutch position.
 14. Theclutch assembly of claim 8, wherein: the clutch assembly input comprisesa first clutch surface; the drive clutch comprises a second clutchsurface that engages the first clutch surface to transmit the secondtorque from the clutch assembly input to the drive clutch when the driveclutch is in the engaged drive clutch position, and does notsubstantially engage the first drive clutch surface when the driveclutch is in the disengaged drive clutch position; and the overloadclutch comprises one or more magnets adapted to hold at least a portionof the second clutch surface in engagement with the first clutch surfacewhen the second drive torque is less than a predetermined torque limit,and disengage at least a portion of the second clutch surface fromengagement with the first clutch surface when the second drive torquereaches a predetermined torque limit to thereby move the overload clutchinto the disengaged overload clutch position.
 15. The clutch assembly ofclaim 2, further comprising: an overload clutch coupled to the driveclutch such that the overload clutch receives the second drive torquefrom the drive clutch when the drive clutch is in the engaged driveclutch position, the overload clutch being moveable between an engagedoverload clutch position in which the overload clutch transmits thesecond drive torque to the clutch assembly output, and a disengagedoverload clutch position in which the overload clutch transmitssubstantially none of the second drive torque to the clutch assemblyoutput; and wherein the overload clutch is located within the drum. 16.The clutch assembly of claim 15, wherein the drive clutch is locatedwithin the drum.
 17. The clutch assembly of claim 1, wherein the starterclutch is biased in the engaged starter clutch position, and the clutchassembly further comprises a starter clutch control mechanism that isselectively operable to move the starter clutch into the disengagedstarter clutch position.
 18. The clutch assembly of claim 1, wherein thesecond drive torque is greater than the first drive torque.
 19. Theclutch assembly of claim 5, wherein the clutch mount comprises theclutch assembly output.
 20. A clutch assembly for a vacuum cleaner, theclutch assembly comprising: a motor adapted to generate a drive torque;a clutch assembly input adapted to be driven by the drive torque; aclutch assembly output adapted to drive an agitator; a drive clutchadapted to selectively transmit at least a portion of the drive torquefrom the clutch assembly input to the clutch assembly output; and astarter clutch adapted to selectively engage the drive clutch bytransmitting a starting torque from the clutch assembly input to thedrive clutch.
 21. The clutch assembly of claim 20, wherein the driveclutch comprises a self-adjusting clutch that increases the drive torqueas a rotational resistance of the clutch assembly output increases. 22.The clutch assembly of claim 20, wherein the starter clutch is not aself-adjusting clutch.
 23. A clutch assembly for a vacuum cleaner, theclutch assembly comprising: a clutch assembly input adapted to be drivenby a motor; a clutch assembly output adapted to drive an agitator; and adrive clutch adapted to selectively transmit a drive torque from theclutch assembly input to the clutch assembly output; wherein the driveclutch comprises a self-adjusting clutch that increases the drive torqueas a rotational resistance of the clutch assembly output increases. 24.The clutch assembly of claim 23, further comprising a starter clutchadapted to selectively engage the drive clutch.
 25. The clutch assemblyof claim 23, further comprising an overload clutch operatively couplingthe clutch assembly output to the agitator, and being adapted tosubstantially terminate the transfer of drive torque from the clutchassembly output to the agitator upon reaching a predetermined torquelimit.
 26. The clutch assembly of claim 23, further comprising anoverload clutch operatively coupling the drive clutch to the clutchassembly output, and being adapted to substantially terminate thetransfer of drive torque from the drive clutch to the clutch assemblyoutput upon reaching a predetermined torque limit.